02Heat remaining 1 tablespoon olive oil in a large skillet over medium-high heat. Add beef, pork, veal and chicken livers, and season with salt and pepper to taste. Cook, breaking the pieces with a wooden spoon, until the meat is no longer pink, about 7 minutes.03Using a slotted spoon, transfer the meat to the sauce. Add rosemary, sage, bay leaves and Parmigiano rind, if using. Cover, and simmer over low heat, stirring occasionally, for 1 1/2 to 2 hours. Discard rosemary, sage, bay leaves and cheese rind. Adjust salt and pepper to taste.04Cook the pasta in a large pot of boiling, lightly salted water until al dente (about 2 minutes for fresh pasta, or follow manufacturer’s directions for dried), then drain well. Divide the pasta among four plates or bowls, and top with ragù.